Carcass Quality Increased Marbling Weaning calves earlier and placing them on a higher grain diet improves marbling, according to researchers at Iowa State University. They conducted a study to evaluate the effects early weaning has on feedlot performance and carcass characteristics. Researchers weaned 120 Simmental- and Angus-sired steer calves at 67 days or 147 days. At 750-800 lbs. the calves were allotted to 16 feedlot pens (7-9 head per pen) by weaning treatment and sire breed.

The early weaned calves were fed a concentrate mixture and long-stem alfalfa hay for 94 days.

Early weaned calves were heavier in initial feedlot weight, but there were no differences on daily gain, dry matter intake, feed efficiency or slaughter weights. Simmental steers required more days on feed than Angus steers.

Hot carcass weight, fat thickness, ribeye area, marbling score and kidney, heart and pelvic fat were measured at slaughter (see Table 1). A ribeye face sliver was collected for the determination of intramuscular (IM) fat by ether extract.

Early weaned calves had a higher percent IM fat, 5.7% vs. 5.1%; higher average marbling scores, Small78 vs. Small20; a higher percentage of cattle grading Choice and higher, 38% vs. 14%; and a higher percentage of Prime, 10% vs. 0%.

For more information contact Dan Loy, Iowa State University, at 515/294-1058 or dloy@iastate.edu.

Real-Time Ultrasound Seedstock producers will be able to avoid long-term and expensive carcass testing programs and use real-time ultrasound to directly scan yearling bulls for body composition traits, claim researchers at Iowa State University.

Their research indicates that traits measured in steer carcasses are directly and highly correlated to traits measured with ultrasound in yearling bulls.

Real-time ultrasound images from more than 27,000 yearling Angus bulls were analyzed to determine adjustment factors and genetic parameter estimates. The traits analyzed included ribeye area, 12-13th rib fat thickness, rump fat thickness and percentage of IM fat (marbling).

EPDs for these traits were computed for the sires that produced the yearling bulls. As accuracy for real-time ultrasound EPD increases, the rank correlation with carcass EPD increases positively.

For more information contact Doyle Wilson, Iowa State University, at 515/294-6914 or dewilson@iastate.edu.

Enhancing Carcass Quality University of Missouri researchers say that cattle can be finished to heavier weights than traditionally done without impacting carcass quality.

The researchers wanted to determine if marbling rate accelerated at a certain point in growth and if carcass quality could be enhanced through diet modifications.

Using Angus crossbred steers, researchers found that the breakpoint at which steers accelerated marbling deposition fat was 64% of their mature body weight. The weight the steers were placed on feed did not affect the weight at which marbling deposition rate accelerated.

Researchers have also been able to enhance carcass quality by providing oil in the diet. They used whole soybeans to introduce vegetable oil into the diet. When whole soybeans were included at 16% or 24% of the diet, 1.25 times more of the steers graded Choice than the control. These improvements occurred in cattle that had been fed whole soybeans for about 60 days.

Funding for this research was provided by the Missouri Soybean Merchandising Council and Missouri Beef Industry Council.

For more information contact Monty Kerley, University of Missouri, at 573/882-0834 or kerleym@missouri.edu.

Feeder Cattle Controlling E. Coli Researchers at the Meat Animal Research Center (MARC) in Clay Center, NE, found that it is possible to reduce fecal shedding of E. coli O157:H7 in feedlot cattle. But, the most successful method was associated with some adverse effects on health of cattle and had obvious negative economic effects.

Researchers looked at three aspects of feedlot calf management, pen sanitation, dietary shifts and transportation. Feedlot cattle were randomly assigned to groups with 50% of each group shedding E. coli O157:H7 in their feces.

Treatments included complete washing of concrete floored pens three times a week, a shift from a standard grain-based feedlot diet to an alfalfa hay-based diet and simulated transport to slaughter including 24-hour feed withdrawal. These studies showed that even a high level of pen sanitation had no effect on the percentage of cattle shedding E. coli O157:H7.

Shifting to a hay-based diet, however, significantly reduced the percentage of cattle with O157:H7 in their feces from 52% to 18% after seven days. Significant economic effects, such as weight loss and increased pulls, were associated with switching to a hay diet. Simulated transport had a similar effect.

For more information contact William Laegreid, MARC, at 402/762-4177 or laegreid@email.marc.usda.gov.

Aerosol Vaccination Louisiana State University researchers suggest that animals should be vaccinated against Pasteurella haemolytica using a nose aerosol.

Vaccination in the lower respiratory tract stimulated a systemic immune response and an immune response in the lung, but did not stimulate an immune response in the nose.

Researchers also showed that the repeated exposure of the lung to even a Pasteurella haemolytica vaccine resulted in decreased clearance of the bacteria from the lung of three calves (out of 11) at 28 days after the first aerosol.

Under field conditions, the failure to clear the bacteria could result in pneumonia (shipping fever).

In shipment, Pasteurella haemolytica colonize in the animal's nose and their lungs are then in jeopardy.

Researchers recommend that cattlemen aerosol-vaccinate their animals two times just prior to movement to sale barns and shipment. This means vaccination at the point of origin (the farm). In this way they should be protected in accumulation and subsequent transit to the feedlot; and, for the first 30 days in the feedlot. This time period is a critical time in determining whether animals will break with pasteurellosis.

For more information contact Richard Corstvet, Louisiana State University, at 225/388-4194 or rcorstvet@agctr.lsu.edu.

Cow/Calf Energy Limits Performance Fifty-four mature beef cows were used in a completely random design to determine supplemental protein requirements when grazing stockpiled bermudagrass pastures during late fall and winter.

Researchers at Oklahoma State University allotted the cows to one of four supplemental treatments at two different locations. Bermudagrass pastures were grazed or clipped to about 2-in. stubble height during late August and fertilized with 50 lbs. of nitrogen per acre. Grazing was deferred until Nov. 3, 1998, at which time grazing and supplemental treatments were initiated and continued for 90 days.

Forage crude protein concentration ranged from 11.6% to 15.3% of dry matter throughout the experiment. Forage protein degradability varied from 50.5% to 67.4% of crude protein.

Supplementation improved overall cow performance, but cows did not respond to additional protein supplementation. In this experiment, energy limited forage utilization and animal performance.

For more information contact David Lalman, Oklahoma State University, at 405/744-6060 or dlalman@okstate.edu.

Hay Supplementation Supplementing heifers with hay will increase gains when grazing ryegrass, whereas supplementing with corn will decrease gains, according to Mississippi State University researchers.

It is common practice for producers to use winter grazing throughout the southeastern U.S. Two of the most prevalent forages used for winter grazing are ryegrass and fescue.

Researchers evaluated energy supplementation for heifers grazing ryegrass and heifers grazing fescue.

For the ryegrass grazing trial, 36 crossbred heifers grazed six, 5-acre paddocks. Each paddock contained six heifers. Animals had either no supplementation, a hay supplement or a corn supplement. Both supplemental groups were fed three times per week to average 2.5 lbs./heifer/day. Every 28 days, heifers were weighed and blood was collected for analysis of blood urea nitrogen (BUN).

Ryegrass dry matter intake was similar for all treatment groups, averaging 8.4 lbs. Heifers grazing ryegrass and receiving a supplement of corn gained slower than those receiving either no supplement or supplemental hay.

Heifers receiving a supplement of hay had lower BUN concentrations than those receiving a supplement of corn during the third and fifth periods.

This would indicate protein utilization was reduced when corn was used as a supplement compared to a supplement of hay.

This data may help explain the faster gains by heifers receiving hay or no supplement, in that they better use the protein in their diet allowing them to gain faster.

In the fescue grazing trial, 24 crossbred heifers grazed four, 5-acre paddocks. Each paddock contained six heifers. Because fescue growth was limiting, animals were allowed ad libitum access to hay. The heifers had either a corn supplement or corn/cotton seed meal supplement. Both supplemental groups were fed three times per week to average 5 lbs./heifer/day. Heifers were weighed every 28 days.

Fescue dry matter intake was similar for all treatment groups, ranging between 5.75 and 7.5 lbs. There were no significant differences in gains for heifers grazing fescue.

For more information contact Brian Rude, Mississippi State University, at 662/325-2802 or brude@beryl.msstate.edu.

Limit Feeding To Save Money Researchers at Oklahoma State University concluded that when forage availability is low, or when hay is expensive, limit feeding grain and/or byproduct feed to cows and developing heifers can save money.

The researchers compared the efficiency of limit-fed fibrous byproduct diets or limit-fed corn diet to free choice hay.

Thirty six Angus and Angus-Hereford crossbred heifers were used in a randomized complete block.

Dietary treatments consisted of: 1) free choice prairie hay plus a soybean meal-based supplement, 2) a whole shelled corn-based diet and 0.5% body weight prairie hay, 3) a wheat middlings/soybean hull-based diet and 0.5% body weight prairie hay, and 4) a barley malt sprout-based diet and 0.5% body weight prairie hay. All diets were fed once daily and contained 200 mg of Rumensin per head.

Weight gains were higher in the three concentrate diet groups. Gains among concentrate diets were not different. Cost per pound of gain was cheapest for the barley malt sprout and corn diets. Based on observed performance, the improvement in dietary energy use was similar among limit-fed corn and limit-fed fibrous byproduct diets (see Table 2).

Conducted at the Willard Sparks Beef Research Center. Funding for the facility was provided through a coordinated effort led by Oklahoma Livestock Industry Foundation.

For more information contact David Lalman, Oklahoma State University, at 405/744-6060 or dlalman@okstate.edu.